The present invention pertains to safe and arming devices and more particularly to fault tolerant electronic safe and arming devices.
The purpose of safe and arming devices is twofold. First the safe and arming device provides for safely storing an explosive device so that it does not detonate prematurely. Second, the safe and arming device arms a detonator of an explosive charge so that the detonator may set off the explosive charge at the desired time.
Electronic safe and arming devices are being developed to replace mechanical and electro-mechanical safe and arming devices for most modern weapons systems. These electronic safe and arming devices typically include a high voltage capacitor, a detonator, triggering electronics and a trigger switch. The triggering electronics send a trigger signal to the trigger switch, commonly implemented with a tube switch, and causes the high voltage capacitor to be charged. When the trigger signal operates the tube switch, the charge stored in the capacitor is transmitted through tube switch to set off the detonator and the subsequent explosive charge.
The tube switch is pressurized with a particular gas mixture and sealed from its environment. The tube is located within the safe and arming device. The tube switch is controlled by the gas mixture and the pressure within the tube switch. If the tube switch leaks, its operating characteristics change. The tube switch can leak in long term storage and cause premature detonation of the explosive device. Destruction of the device delivering the explosive, such as a plane, or explosion substantially far away from a target may result. Either result is undesirable.
Accordingly, it would be desirable to have a fault tolerant safe and arming device.